Electrochemical processes include anodic and cathodic processes. For various reasons, energy conservation being paramount, it has been found desirable to employ undivided cells in many of such processes. Undivided cells, as a general rule are more efficient, so far as electrical consumption is concerned, than divided or membrane-type cells; but they have the disadvantage that a free interflow of the electrolyte, as well as electricity may result in a competing gas migrating to the reaction electrode. By "competing" is meant any gas which may consume electricity while being reduced or oxidized.
For example, electrochemical reduction processes, particularly those for the production of paraffinic dinitriles, dicarboxamides or dicarboxylates by electrolytic hydrodimerization of an alpha, beta-olefinic nitrile, carboxamide or carboxylate are well known. (U.S. Pat Nos. 3,193,475-79 and 3,193,481-83 issued July 6, 1965, to M. M. Baizer). Although such processes have been sufficiently attractive that they have been in commercial use for over fourteen years, efforts to develop improvements thereon have been continued with particular emphasis on lowering electric power costs and mitigating electrode corrosion and fouling tendencies because of which it has been heretofore commercially preferable to carry out the process with a cell-dividing membrane.
With the object of maintaining high electrolyte conductivity while employing an electrolysis medium containing organic salts in a proportion small enough for attractive use of a single-compartment (membraneless) cell, one approach to improvement of the process has been to use as the electrolysis medium in aqueous solution of a mixture of quaternary ammonium and alkali metal salts together with the olefinic compound to be hydrodimerized. An example of such an approach is described in Netherlands Patent Application No. 66,10378 laid open for public inspection Jan. 24, 1967, and further development thereof is described in U.S. Pat. No. 3,616,321 issued Oct. 26, 1971, to A. Verheyden et al. and U.S. Pat. No. 3,689,382 issued Sept. 5, 1972, to H. N. Fox et al. However, all known variations of the process are characterized by some degree of inefficiency in use of the electrolyzing current, and this problem is typically more significant in those process variations using an undivided cell.
Clearly, the higher the proportion of the electrolyzing current that reduces molecular oxygen rather than the desired hydrodimer, the greater the cost of production of the hydrodimer will be. Accordingly, a process improvement whereby an olefinic compound can be electrolytically hydrodimerized with a resulting lowered reduction of molecular oxygen and a thereby increased current efficiency is highly desirable, and it is an object of this invention to provide such an improvement. Additional objects of the invention will be apparent from the following description and Examples in which all percentages are by weight except where otherwise noted.